If 10 grams of NaCl is dissolved in 500 mL of water, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)
Practice Questions
1 question
Q1
If 10 grams of NaCl is dissolved in 500 mL of water, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)
0.34 m
0.17 m
0.85 m
0.50 m
Molality (m) = moles of solute / kg of solvent. Moles of NaCl = 10 g / 58.5 g/mol = 0.171 moles. Mass of water = 0.5 kg. Molality = 0.171 moles / 0.5 kg = 0.342 m.
Questions & Step-by-step Solutions
1 item
Q
Q: If 10 grams of NaCl is dissolved in 500 mL of water, what is the molality of the solution? (Molar mass of NaCl = 58.5 g/mol)
Solution: Molality (m) = moles of solute / kg of solvent. Moles of NaCl = 10 g / 58.5 g/mol = 0.171 moles. Mass of water = 0.5 kg. Molality = 0.171 moles / 0.5 kg = 0.342 m.
Steps: 7
Step 1: Identify the mass of NaCl (the solute) which is given as 10 grams.
Step 2: Identify the molar mass of NaCl, which is given as 58.5 g/mol.
Step 3: Calculate the number of moles of NaCl using the formula: moles = mass (g) / molar mass (g/mol). So, moles of NaCl = 10 g / 58.5 g/mol.
Step 4: Perform the calculation: 10 g / 58.5 g/mol = 0.171 moles of NaCl.
Step 5: Identify the volume of water (the solvent) which is given as 500 mL. Convert this to kilograms: 500 mL of water = 0.5 kg (since 1 L of water = 1 kg).
Step 6: Use the formula for molality: molality (m) = moles of solute / kg of solvent. Substitute the values: molality = 0.171 moles / 0.5 kg.
Step 7: Perform the calculation: 0.171 moles / 0.5 kg = 0.342 m.
